<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>

<style>
    *{
        height: 100%;
        width: 100%;
    }
    .all{
        height: 600px;
        width: 600px;
        border: solid 5px;
        border-color: red;
        position: relative;

    }
    .all #message{
        height:350px ;
        width: 595px;
        overflow: auto;

    }
    #username{
        height: 90px;
        width: 595px;

    }
    #text{
        height: 116px;
        width: 595px;
    }

    button{
        height: 30px;
        width: 70px;
        display: flex;
        display: inline;

    }
    input{
        width: 100px;
    }
</style>

<body>
Welcome<br/>
<div class="all">
    <p id="message" style="color: blue" >[状态]  </p>
    <input type="text" id="username" value="" placeholder="昵称：">
    <input value="" id="text" type="text"  placeholder="内容："/>

</div>

<button type="button" onclick="send()">发送</button>
<button onclick="closeWebSocket()">关闭</button>
</body>

<script type="text/javascript">
    window.onload = function () {
        //判断当前浏览器是否支持WebSocket
        if ('WebSocket' in window) {
            websocket = new WebSocket("ws://localhost:80/websocket");
        } else {
            alert('当前浏览器 Not support websocket')
        }

        //连接发生错误的回调方法
        websocket.onerror = function () {
            setMessageInnerHTML("WebSocket连接发生错误");
        }

        //连接成功建立的回调方法
        websocket.onopen = function () {
            setMessageInnerHTML("WebSocket连接成功");
        }
        //接收到消息的回调方法
        websocket.onmessage = function (event) {
            setMessageInnerHTML(event.data);
        }
        //连接关闭的回调方法
        websocket.onclose = function () {
            setMessageInnerHTML("WebSocket连接关闭....");
        }

        //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
        window.onbeforeunload = function () {
            closeWebSocket();
        }
    }

    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }

    //发送消息
    function send() {
        var div = document.getElementById("message");
        var username = document.getElementById('username').value;
        var message = document.getElementById('text').value;
        var msg = "[" + username + "]:" + message;
        div.scrollTop = div.scrollHeight;
        console.log( div.scrollHeight)
        websocket.send(msg);
        document.getElementById('text').value="";
    }

    //关闭WebSocket连接
    function closeWebSocket() {
        websocket.close();
    }
</script>
</html>